The amnesic effect of adenosine is mimicked by A1 and A3 receptor agonists infused together. Male Wistar rats with infusion cannulas implanted into the CA1 region of the dorsal hippocampus were trained for 5 d in the spatial version of the MWM. Twenty-four hours after the final training session, the animals were subjected to a 60-sec probe test in the absence of the escape platform. Immediately after this first test, the animals received intrahippocampal bilateral infusions (black arrow) of either saline solution (saline) or A1 (ago A1), A2A (ago A2A), A2B (ago A2B), A3 (ago A3), or A1 plus A3 (ago A1 + A3) receptor agonists (10 nmol for each agonist). Memory retention was assessed in successive 60-sec probe tests carried out either 24 h or 5 d after the first test. Data are expressed as means (±SD) of the percentage of swimming time spent in the target quadrant. (Dots) Individual value for each rat, (dashed line) theoretical mean of 25% of test time spent in the target quadrant at random. (*) P < 0.05, (**) P < 0.01 versus respective saline groups; one-way ANOVA: test 24 h after the first test, F(5,44) = 2.690; test 5 d after the first test, F(5,44) = 3.513; Dunnett's posttest; n = 6–12 per group.
